Points for travel is often a prime perk for using credit cards. Building up miles toward a flight or points toward a hotel is how many people save for a much-needed getaway.

But have you checked your points lately? Someone else may be taking a grand vacation - on you.

Flights, hotels, rental cars, even entire trips, all for sale - not by regular travel agents, but by criminals setting up shop selling stolen rewards points.

"In the deep and dark web there are these travel agencies, and they're run by these vendors who advertise that they can get you pretty much anything that you would need for vacations to anywhere in the world," said Liv Rowley, an intelligence analyst with Flashpoint.

Those stolen rewards are usually at a major discount.

Rowley spends her day monitoring the dark web for fraud.

She says criminals use various software tools to nab your points.

"It's really important to see in the deep and dark web that this is not one person who's doing it all. It's often times groups of people that work together to accomplish fraud," said Rowley.

Rowley says a scammer will steal, for example, your flight miles and sell them to a criminal travel agent who takes other stolen points for something like a hotel and pool them together.

It's so brazen, there are ratings systems.

"It's unfortunate, but it's not all that shocking given the high value of the points and miles," said Emily McNutt, the associate editor for The Points Guy, a website about travel points.

Many people often don't know their miles are stolen until sometimes months after they're gone.

McNutt says that's one reason the bad booking agents are able to set up shop.

"People know how to keep their bank accounts secure, they know how to check on their balances and make sure everything is up to date," she said. "However, unfortunately in the points and miles world, we don't always see that."

You can protect yourself with strong passwords, including different passwords for various accounts.

Make sure to also sign up for alerts, so that if your points are redeemed, you are the first to know.

"Consumers should look at points and miles as money," said McNutt.

While points programs aren't required to offer the same protection as credit cards, McNutt says many will stand by their customers.

She says if your points are stolen, call the provider as soon as possible to see what the company may be able to do to credit the points back to your account.